feat: Add --templated flag to pixi run

[pavelzw]

Description

closes #5478

Fixes #{issue}

How Has This Been Tested?

❯ ./target/debug/pixi run 'echo' '{{ pixi.version }}'
{{ pixi.version }}
❯ ./target/debug/pixi run --templated 'echo' '{{ pixi.version }}'
0.63.2
❯ ./target/debug/pixi run example
✨ Pixi task (example in default): echo osx-arm64
osx-arm64
❯ ./target/debug/pixi run --templated example
Error:   × --templated has no effect for manifest-defined task 'example' (tasks in the manifest are always templated)

AI Disclosure

• This PR contains AI-generated content.
  • I have tested any AI-generated content in my PR.
  • I take responsibility for any AI-generated content in my PR.

Tools: Claude Code

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.
• I have verified that changes that would impact the JSON schema have been made in schema/model.py.

[ruben-arts]

Why would you error on using --templated when it doesn't do anything?

[pavelzw]

it implies that without using --templated, it would actually not template things. but i also don't feel super strong about this, can also revert that part

[ruben-arts]

it implies that without using --templated, it would actually not template things. but i also don't feel super strong about this, can also revert that part

I rather not error when it doesn't change the outcome, so please remove that.

[ruben-arts]

Thank you! Works for me